Re: [PATCH 02/11] mm,migration: Do not try to migrate unmapped anonymous pages

From: KOSAKI Motohiro
Date: Thu Mar 25 2010 - 23:07:17 EST


very small nit

> There were minor changes in how the rcu_read_lock is taken and released
> based on other comments. With your suggestion, the block now looks like;
>
> if (PageAnon(page)) {
> rcu_read_lock();
> rcu_locked = 1;
>
> /*
> * If the page has no mappings any more, just bail. An
> * unmapped anon page is likely to be freed soon but
> * worse,
> * it's possible its anon_vma disappeared between when
> * the page was isolated and when we reached here while
> * the RCU lock was not held
> */
> if (!page_mapcount(page) && !PageSwapCache(page))

page_mapped?

> goto rcu_unlock;
>
> anon_vma = page_anon_vma(page);
> atomic_inc(&anon_vma->external_refcount);
> }



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